I am running an X2 4600 with 2Gb and a Radeon X1950XT and can run 3 and 5 instances of Wow on it. albeit on one screen (I have 3 attached, 2 through a 2400pro) but unplayable on all if I have them split over more than one screen.

I am running XP

resolutions for my windows are
main : 1200x600 with sound
1: 720x700 no sound
2 - 5: 640x500